89 accord lxi.
Recently started having problems with my tranny. If I drive slow, I can shift into all gears. When I'm going fast, it "lags" on me. For example, I can take off in first just fine, if I take off fast and try to shift like at 20mph, it'll go into 2nd gear but not all the way? Because then I gas it and the rpms shoot up, then I have to just let the car keep rolling and it'll eventually find the gear and go in fully. Its strange to me.
Is it the clutch starting to fail? Or a broken shift fork? Or gears?
I will be checking my cable for looseness tmrw, car only has 147k.

 

Check that your shift linkage is not loose or worn out, same with the clutch linkage.

If the clutch was worn out then when in a higher gear(higher load on the clutch) it would slip more. 1st doing 15MPH no slippage, 5th gear at highway speed would cause slippage.

When the car is stopped/off and you clutch in, does it easily shift into each gear or does it feel vague?

Does this shift feeling change depending on if the car is cold or hot?

Any noises from the transmission? Is the fluid full/been changed during normal service?